Voltmeter Voltage

[Fat Fender]

When using a stock '40 voltmeter in a car that's being converted to 12V, do I need to reduce the voltage to the voltmeter or is it voltage independent like an ammeter? I've already reduced the voltage to the gas, oil and temp guages.

Thanks for any advice.

[19Fordy]

Originally Posted by Fat Fender

When using a stock '40 voltmeter in a car that's being converted to 12V, do I need to reduce the voltage to the voltmeter or is it voltage independent like an ammeter? I've already reduced the voltage to the gas, oil and temp guages.

Thanks for any advice.

When I converted from 6 to 12 volt I used used a resistor in the line that feeds the BATT volt meter otherwise it won't read correctly and I think you will fry it if you send 12V thru it. Thanks to an electrical wizzard on HAMB named FLAT ERNIE I was able to make it all work. The sketch below shows how I rewired my instrument cluster. You must remove the brass strip between the BATT and OIL gauges and use a 60 ohm resistor in the 12V hot wire that feeds your BATT gauge. I bought the resistor on line for about 40 cents. This means the BATT gauge is isolated by itself and is being fed by the one 12V wire with the resistor in it. A constant voltage reducer is then used to feed 6V to the TEMP, FUEL and OIL gauge. The stock brass strip between the FUEL and TEMP gauge remains in place because that feeds the FUEL gauge. However, another wire is hooked up between the TEMP gauge and the OIL gauge. Rather than have a bunch of wires coming off the ignition switch a friend of mine installed a fuse block on the fire wall under the dash to make the wiring easier and safer. Feed 12 V to that and then run your other wires off of it. All the gauges work fine. The TEMP gauge shows cold in the photo as I just started the car. It was also low on gas. Electricity is not my thing, so I hope the photos help. My thanks to Flat Ernie and my friend Joe for helping me.

[Fat Fender]

19Fordy - Thanks for taking the time to send me the diagram and explanation. I'm no electrical whiz, but I think I can follow what you did. Simple enough. I knew I couldn't be the first one facing this problem.
Fat Fender

[Flat Ernie]

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I'm no electrical wizzard by a long shot!

19Fordy has summed it all up perfectly! His system works!